1. Field of the Invention
The present invention relates to an electropneumatic actuator system for operating assemblies of an internal combustion, and a method for regulating the actuator system.
2. Description of Related Art
Within the scope of motor vehicle actuating systems, pneumatic actuators are used in the automotive field, these days. The pneumatic actuators are predominantly developed as pressure boxes, which are able to be operated both using an overpressure or a partial vacuum. The pressure boxes are generally not controlled electronically, and they are developed in such a way that the pressure prevailing in the pressure boxes, such as a boost pressure, act directly on a spring or a diaphragm. In pressure boxes used on charging devices for internal combustion engines, especially on exhaust-gas turbochargers, the actuating position of the actuator of the pressure box is controlled in an electronic manner by actuating a pulse valve using a PWM signal from a boost pressure controller. The actuated pulse valve sets the pressure of the pressure box, or the position of the actuator of the pressure box, required for a boost pressure/setpoint value comparison or a boost pressure/actual value comparison. The pulse valve may be provided both externally, as, for instance, in the supply line to the pressure box, or it may be integrated into the pressure box. When it comes to a state regulation with regard to the position of the actuator of a pressure box, very costly electronic regulations are required. In particular in the case of self-igniting internal combustion engines, to which a charging device has been allocated which may be an exhaust-gas turbocharger, designed to have an adjustable turbine geometry, as a result of the coupling between the exhaust gas recirculation and the boost pressure regulation a regulation is, however, increasingly urgently required of the position of the actuator of the pressure box. For the implementation of this, only relatively costly electrical actuators come into consideration, that have position feedback and electronic position control, which, on the one hand, may be assigned directly to the charging device having adjustable turbine geometry or are integrated into the engine control unit of an internal combustion engine.
A charging device is known from published European patent document EP 0 976 919, which is developed as an exhaust-gas turbocharger and includes a wastegate. An actuating rod is used for the boost pressure regulation on the exhaust-gas supercharger, and it has a first rod section and a second rod section. The two rod sections of the actuating sections are coupled to each other rotatably, and may be rotated with respect to each other. A lever is operated, using the actuating rod, which on its part is coupled to the wastegate of the exhaust-gas supercharger.